Patent GB-732495-A (GB)
Title: Method of and apparatus for the production of helically grooved tubes or pipes
IPC: B21C37/12
Filed: 1953-01-12
Abstract: 732,495. Machines for making flexible tubes. HEGLER, W. Jan. 12, 1953 [Jan. 17, 1952], No. 944/53. Class 99 (2). [Also in Group XXII] Helical grooves are formed in tubing comprising, wound paper or sheet metal webs, or both, by engagement of the wall of the tube between a threaded mandrel 15 and the external peripheries of a number of wheels or rollers which are mounted around and bodily rotated around and in the same direction as the mandrel. The tube and mandrel are rotated in the same direction about their axes, and the wheel or roller peripheries are so formed and the wheel or roller movements are so related to the thread of the mandrel and its rotation that the wall of the tube is pressed into the grooves of the mandrel and the grooves are formed along the tubing as the latter advances over the mandrel. As shown in Fig. 1, a paper web 2 drawn from a roll 1 rotating about its own axis and the tube-forming axis of the machine is shaped into longitudinally split tubing in a tube 3 which rotates with the split tubing. The split tubing runs on to a winding mandrel 4 rotating with the tube 3. Paper or metal webs 14, or both, drawn from rolls 12, 13 rotatable about fixed axes are helically wound onto the mandrel 4 and over the split tubing. The tube 3 is rotated by gears 6, 7, and a tube 5 mounted within the mandrel 4 and driving the mandrel 15 has a gear 11 driven through a gear 8 rolling on a fixed, toothed annulus 10 and mounted on an arm 9 connected to the tube 3. A shaft 20 carries the gear 6 and an identical gear 18 which meshes with a gear 19 driving a head through a hollow shaft 17, the head being rotated at the same speed as the tube 3 and carrying a number of radially disposed worm wheels 16 having inclined teeth adapted in form to the thread of the mandrel. The wheels 16 are mounted in brackets 24 and rotated about their axes by worms 21 rotated by the rolling of gears 22 on a fixed, toothed annulus 23 ; alternatively, the wheels are driven by planetary gearing. To enable the wheels 16 to be moved in a radial direction so that the pressure of the wheels may be adjusted to suit the material of the tubing the brackets 24 are displaced by studs 26, Fig. 3, engaging in the brackets and eccentrically disposed to pins 27 which support gears 28 engaging an annular gear 29. Rotation of the gear 29 causes simultaneous turning of the pins 27 to move the wheels towards or away from the axis of the machine. In order to prevent the overlapping convolutions of the outermost strip 14 from opening when the tubing is bent in use, the margins of the strip may be turned over in opposite directions substantially at right angles to the plane of the strip as shown in Fig. 5. the margin 30 being directed outwardly and engaged by the trailing margin 31 of the adjacent turn of the strip. Due to the pull on the strip the engaged margins are pulled one into the other and secured by a pressure roller. Where a wax or like impregnated paper is used for the inner layers of the tubing the heat generated internally of the tubing by the friction of the threaded mandrel may be utilised to weld the paper layers together during the impression of the grooving in the tubing. In a modification, the wheels 16, Fig. 6, are replaced by axially disposed rollers 32 provided with annular grooves and freely rotatable on axles 36 eccentrically connected to pins 38 carrying gears 39 engaging an annular gear 40 whereby the rollers are simultaneously displaced in the radial. direction. The mandrel is adjoined by a cylindrical part 41 connected to the mandrel 4 by a shaft 43 extending through the tube 5, the part 41 co-operating with cylindrical portions of the rollers 32 so that the crests of the corrugations in the tubing are flattened.